dt-bindings: usb: Add V3s compatible string for EHCI

The Allwinner V3s uses a generic EHCI and OHCI for USB host
communication and the MUSB controller for OTG mode. Add compatible
strings for the EHCI node.

Signed-off-by: Chris Morgan <macromorgan@hotmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230828181941.1609894-5-macroalpha82@gmail.com


Signed-off-by: Rob Herring <robh@kernel.org>